This project aims to shed light on brain mechanisms underlying mammalian learning and memory. The rodent olfactory bulb is chosen as the object of study because it is a large, well-developed and readily-accessible brain structure exhibiting "cortical" features of organization normally associated with the mediation of neurobehavioral plasticity. Electrophysiological measures of sensitization and habituation to electrical stimulation of restricted cell regions are made with the aid of a new fine wire semimicroelectrode. Subsequent studies will attempt to identify and localize a structural basis for these effects using electron microscopical techniques.